What operating system are you using? What word processor (Word, LibreOffice, printing directly from Zotero)? What printer? This does sound like an odd text encoding issue. Changing the typeface might help.

This is a character encoding issue as @adamsmith said. Specifically, the dash that separates page numbers isn't recognized as being a legitimate character in the font table. Another possibility is that the non-breaking (keep-together) command character is treated as an unrecognized printable character.

Someone may be able to suggest to you how you can make modifications to the citation style to eliminate the printing problem. An alternative might be to change the default character set within Microsoft Word. Someone familiar with Word will be able to tell you how to do this.